Scanning and recording device for electrostatic recording

ABSTRACT

A scanning and recording device for electrostatic recording which comprises a dielectric sheet sandwiched between two electroconductive sheets, one of said conductive sheets being photoetched into the form of the multistylus, the other conductive sheet being used as a ground electrode, one of the end portions of said sandwiched sheets being made into a cylindrical shape to be used as the scanning head, and the flat and straight end surface at the other end of said sheets being used as the recording head, said device being suitable for an operation at a high scanning rate without necessitating any special electronic tube as recording element.

Inventors Masaru Ohno;

Kimitaro Suzuki, Tokyo, Japan 770,318

Oct. 24, 1968 Apr. 27, 1971 Toho Denki Co., Ltd.

Tokyo, Japan Appl. No. Filed Patented Assignee SCANNING AND RECORDINGDEVICE FOR ELECTROSTATIC RECORDING 6 Claims, 10 Drawing Figs.

3,307,198 2/1967 Morgan 346/74 Re26,212 5/1967 Johnson et al. 346/743,380,070 4/ I 968 Betts et al.. 346/74 Primary Examiner-Bernard KonickAssistant ExaminerGary M. Hoffman Attorney-lecies and GreensideABSTRACT: A scanning and recording device for electrostatic recordingwhich comprises a dielectric sheet sandwiched'between twoelectroconductive sheets, one of said conductive sheets beingphotoetched into the form of the multistylus, the other conductive sheetbeing used as a ground electrode, one of the end portions of saidsandwiched sheets being made into a cylindrical shape to be used as thescanning head;and the flat and straight end surface at the other end ofsaid sheets being used as the recording head, said device being suitablefor an operation at a high scanning rate without necessitating anyspecial electronic tube as recording element.

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7 2 23 FIG. 5 l PRIOR ART T TC T 1 INVENTOR Masaru Ohno and KimitaroSuzuki By Their Attorneys ATTORNEY PATENTED APRZTIQYI SHEET 2 BF 2 FIG.6 PRIOR ART SLB-SCANNING AIN SCANNING FIG. a

nun u nun u on. N on 28 noun anon on INVENTOR Masaru Ohno and mitaroSuzuki nv fl wfkw heir Attorneys ATTORNEY SCANNING AND RECORDING DEVICEFOR ELECTROSTATIC RECORDING BACKGROUND OF THE INVENTION I. Field of theInvention Thisinvention relates to a scanning and recording device forelectrostatic recording in a facsimile system, particularly to such adevice utilizing a multistylus electrode.

2. Description of the Prior Art Generally speaking, the recordingprocess with an electrostatic. recording system comprises the steps of,causing a recording stylus to .contact the surface of an electrostaticrecording paper which is coated with an insulating resin or the like,applying a signal voltage of several hundred volts to said recordingstylus thereby to produce a latent image of electrificationcorresponding to said signal voltage on said insulating layer of resin,and developing and fixing said latent image to obtain a visiblerecording. Such a process with which an electrostatic latent image isdirectly produced by electrical means, requires a comparatively highvoltage but little recording current. Therefore, such a recordingsystemis economical in power consumption, suitable for high-speed recordingand produces a distinct record of good contrast on white paper.

In one'conventional electrostatic recording system, it is a commonpractice to adopt a planar scanning system, as it is convenient tocontinuously advance the recording paper for the developing and fixingprocess after the electrostatic latent image has been produced. Typicalexamples of the conventional electrostatic recording systems will bedescribed hereunder.

Endless belt-type scanner comprises a plurality of metallic stylusesplanted at uniform spaces on an endless belt extended between a pair ofpulleys, the recording being performed by imposing the signal voltage onsaid styluses which scan a dielectric recording paper in contact withsaid paper. This system is not advantageous in regard to the followingpoints that it is not suitable for high-speed scanning, that thereproduced picture is deteriorated by the frictional electrification asthe styluses are run in contact with therecording paper, and that it isshort in service life because of damage to the belt and othercomponents.

Other conventional electrostatic recording systems include planarscanning systems in which the ends in one side of a number of insulatedconductors are aligned uniformly to form a multistylus electrostaticrecording head and the other ends are connected to a signal distributorwhich comprises terminals disposed in a circle and a rotatingwiper, andwith which the electrostatic recording is performed on a recording paperwhich moves adjacent to the recording head, the image signal introducedthrough said signal distributor being led to said styluses in therecording head. A great disadvantage of this system is that it is notsimple nor easy to construct.

A further example of the conventional scanning systems is theelectrostatic recording tube which is a cathode ray tube whose faceplateis provided with an array of a number of styluses penetratingtherethrough, said array of styluses being scanned at their inner endswith the electron beam whose intensity varies in, correspondence withthe image signal voltage, and thus the electrostatic recording beingmade on a recording paper which is passed adjacent tothe faceplate.Though this known system is suitable for high-speed scanning, it has agreat disadvantage in regard to the following points that such anelectrostatic recording tube is difficult to fabricate and very high incost.

SUMMARY OF THE INVENTION An object of this invention is to provide ascanning and recording device for electrostatic recording comprising twoelectroconductive sheets attached to both surfaces of a dielecformed inone of the end portions of said sandwiched sheets, and a cylindricalscanningportion formed in the other end portion of said sandwichedsheets.

Another object of this invention is to provide a scanning and recordingdevice for electrostatic recording wherein said electrostatic recordinghead in said one end is inclined against the recording paper in order toincrease the area of the end of a stylus in contact with the recordingpaper.

This invention has eliminated the previously mentioned disadvantages ofthe conventional systems, and has made it possible to effect ahigh-speed scanning with a simple structure. Further, according to thisinvention, an increased density of recording is obtained, as the shapeof an elementary dot of record which was conventionally a circle is madean ellipse thereby to fill more area in the space between subscanningsor two rows of main scanning.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric view ofsandwiched sheets used in this invention;

FIG. 2 is a side view of the sandwiched sheets shown in FIG.

FIG. 3 is an isometric view of an embodiment of the scanning andrecording device of this invention;

- FIG. 4 shows an equivalent circuit of the capacitance betweenconductors of the sandwiched sheets;

FIG. 5 is a schematic diagram illustrating a conventional scanningsystem;

FIG. 6 is an example of a record made by the conventional system shownin FIG. 5;

FIG. 7 is a schematic diagram illustrating the scanning and recordingdevice of this invention in use;

FIG. 8 is an example of a record made by the device shown in-FIG. 7;

FIG. 9a is an isometric view of another embodiment of the scanning andrecording device of this invention; and

FIG. 9b is an enlarged view of a portion of the device shown in FIG. 90.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A scanning and recording deviceof this invention comprises a sandwiched formation including twoelectroconductive sheets attached to both surfaces of a dielectricsheet, one of the electroconductive sheets being photoetched to form amultistylus and the other of the electroconductive sheets being used asa ground electrode.

Referring to FIGS. I and 2, the multistylus 2 is seen to be provided onone surface of the dielectric sheet 1 and the ground electrode 3 on theother surface. One end portion of the above-described sandwiched sheetsis formed into a cylinder to be used as a part of the scanner ordistributor, while the other end portion is maintained flat and straightand is solidified with a synthetic resin or the like to be formed into arecording head 4. In this embodiment, the above-mentioned cylindricalportion is formed with the multistyluses 2 outside and the groundelectrode 3 inside. As shown in FIG. 3, a pair of brushes 6 and 7 areprovided in contact with said cylindrical portion and a high voltagecorresponding to image signal is applied to said brush 6 while saidbrush is rotated around the cylindrical portion. Thus, on the other endof the device, an

electrostatic image isobtained through the recording head 4 on arecording paper 5 which is moved in the direction perpendicular to thelengthwise direction of the recording head. The thus obtainedelectrostatic latent image is turned to a visible image throughdevelopment with a toner.

In FIG. 4 which shows an equivalent circuit of the capacitance betweenconductors, each conductor 2,, 2 2 leading to each stylus is seen on onesurface of the dielectric sheet 1. In operation, when a signal voltageis applied to a stylus or conductor through the brush 6, a voltage isinduced in the adjacent conductors owing to the static capacitancesC C2, between the conductors. The charge distribution due to the leakage ofthe image signal voltage to adjacent conductors' remarkably lowers theresolution of the picture in the direction of the main scanning. Toprevent the above-mentioned deterioration of the resolution, the aroundelectrode 3 is provided opposite to the conductors of the multistylus.

I Thus, the effects of the static capacitances C C between adjacentconductors are reduced by the capacitances C', C", C', betweenrespective conductors and the ground. For example, assuming that asignal voltage V is applied to the stylus or conductor 2, through thebrush 6, voltage V, induced in the adjacent conductor 2, or 2;, isdivided between C and C, or between C, and C' as shown by the followingformula:

, 14 a cushion for urging the recording paper 13 against the stylus 11',15 a scanner, and 16 an amplifier. In this arrangement, if a voltagerelated to the input signal is applied to the conduc tor or stylus 11,the recording paper is electrified at the spot where said stylus is incontact with the paper, thus a latent image being made on the paper.This latent image is turned to a visible image as shown in FIG. 6through the development. In FIG. 6, a visible image 18 is seen on therecording paper 13. Electrification of the recording paper and amount ofthe toner deposited on the latent image vary depending on characteristics of the recording paper and the developing agent, and thedensity of the record is limited. Assuming that the space betweenadjacent styluses is a and the space of the subscanning is b as shown inFIG. 6, it is required for obtaining a satisfactory apparent density toreduce the spaces a and b as much as possible. In a high-speed recordingwith low density scanning, the space b is inevitably coarse resulting inlow apparent density. According to this invention, the recording head 22is positioned in such a manner that the multistylus 21 is inclinedagainst the recording paper 23 at an angle as shown in FIG. 7. In FIG.7, reference numeral 24 indicates a cushion for urging the recordingpaper 23 against the stylus 21, numeral 25 the ground electrode, 26 ascanner, and 27 an amplifier. In this arrangement, if a voltage relatedto the input signal is applied to the stylus 21, the recording paper iselectrified at the spot where said stylus is in contact with the paper,thus a latent image being made on the paper. This latent image is turnedto a visible image as shown in FIG. 8 through the development. In FIG.8, a visible image 28 is seen on the recording paper 23. An elementarydot of the image has the shape of an ellipse in FIG. 8, whereas it is acircle in FIG. 6. The length of the long axis of the ellipse isdetermined by the angle 0, and so is the space C between adjacent dotsin the direction of the subscanning. Effects of this arrangement will befurther explained hereunder.

Assuming that the multistylus included m/mm elementary styluses, thediameter of each stylus being 7 mm and that the rate of subscanning isF-lines/mm, the conventional system as shown in FIG. 5 will produce arecord in which the center distance b between adjacent dots in thedirection of subscanning is HF and the space between dots in the samedirection is HP 7. According to this invention, each of the elementarydots of the record assumes the shape of an ellipse as shown in FIG. 8owing to the inclination of the stylus by the angle 6, thus the lengthof the long axis of the ellipse being 'y/cos 0 and the space 0' betweenadjacent lines being l/F-*y /cos 0. As y/cos 0 is larger than y in therange of 0 0 90, the space C in FIG. Bis smaller than the space C inFIG. 6. Thus, the apparent density of the image in the direction of thesubscanning is improved.

FIGS. 9a and 9b show another embodiment of the scanning and recordingdevice of this invention. In this embodiment, the cylindrical endportion of the device is formed with the multistylus 102 inside and theground electrode 103 outside, contrary to the embodiment shown in FIG.3. The dielectric sheet is indicated by numeral 101 in the FIG. Scanningis performed by applying a high voltage corresponding to an image signalto the brush 106 while said brush is rotated inside the cylindricalportion. Thus, on the other end of the device, an electrostatic latentimage is obtained through the recording head 104 on a recording paperwhich is moved in the direction of the subscanning. Another brushl07'which is grounded is rotated with the brush 106 but a bit behind itto eliminate the residual electricity. In this embodiment too, thefeature of the inclined stylus as shown in FIG. 7 may be included inorder to improve the recording density.

We claim:

1. A scanning and recording device for electrostatic recording,comprising a pair of electroconductive sheets each of which issubstantially planar, a dielectric sheet disposed between andsubstantially coextensive with said electroconductive sheets to form asandwich therewith, one of said electroconductive sheets beingphotoetched to provide raised portions comprising styluses the other ofsaid electroconductive sheets being adapted to serve as a groundelectrode, one end of said sandwich being formed in the shape of acylinder and adapted to serve as a scanner, the other end of saidsandwich presenting a substantially planar recording head, and the saiddielectric sheet being of substantial thickness relative to thedistances between said styluses so as to thereby reduce the staticcapacitance between said styluses and thus improve resolution of therecorded picture.

2. A scanning and recording device as defined in claim 1, wherein saidstyluses are inclined against the recording paper at a certain angle.

3. A scanning and recording device as defined in claim 1, wherein saidcylindrical portion is formed with said styluses on the outside of thecylinder.

4. A scanning and recording device as defined in claim 3, wherein saidstyluses are inclined against the recording paper at a certain angle.

5. A scanning and recording device as defined in claim 1, wherein saidcylindrical portion is formed with said styluses on the inside of thecylinder.

'6. A scanning and recording device as defined in claim 5, wherein saidstyluses are inclined against the recording paper at a certain angle.

1. A scanning and recording device for electrostatic recording,comprising a pair of electroconductive sheets each of which issubstantially planar, a dielectric sheet disposed between andsubstantially coextensive with said electroconductive sheets to form asandwich therewith, one of said electroconductive sheets beingphotoetched to provide raised portions comprising styluses the other ofsaid electroconductive sheets being adapted to serve as a groundelectrode, one end of said sandwich being formed in the shape of acylinder and adapted to serve as a scanner, the other end of saidsandwich presenting a substantially planar recording head, and the saiddielectric sheet being of substantial thickness relative to thedistances between said styluses so as to thereby reduce the staticcapacitance between said styluses and thus improve resolution of therecorded picture.
 2. A scanning and recording device as defined in claim1, wherein said styluses are inclined against the recording paper at acertain angle.
 3. A scanning and recording device as defined in claim 1,wherein said cylindrical portion is formed with said styluses on theoutside of the cylinder.
 4. A scanning and recording device as definedin claim 3, wherein said styluses are inclined against the recordingpaper at a certain angle.
 5. A scanning and recording device as definedin claim 1, wHerein said cylindrical portion is formed with saidstyluses on the inside of the cylinder.
 6. A scanning and recordingdevice as defined in claim 5, wherein said styluses are inclined againstthe recording paper at a certain angle.